Cytotoxic Epipolythiodioxopiperazines from the Deep-Sea-Derived Fungus MCCC 3A00939.

Four new aranotin-type epipolythiodioxopiperazines, graphiumins K-N (-), along with four known analogues (-), were isolated from the deep-sea-derived fungus MCCC 3A00939. Their structures were elucidated by detailed interpretation of NMR and mass spectrometric data. The absolute configuration of the isolates was deduced by a single-crystal X-ray diffraction analysis and the comparisons of experimental electronic circular dichroism (ECD) data with calculated ECD spectra. Graphiumins K () and L () exhibited cytotoxic activities against the K562, H69AR, and MDA-MB-231 cancer cells with IC values ranging from 2.3 to 5.9 μM.